1. Field of the Invention
The present invention relates to content reproduction apparatuses and content processing methods, which reproduce audio content in conjunction with video content.
The present application claims priorities on Japanese Patent Application No. 2010-270269 filed Dec. 3, 2010, and Japanese Patent Application No. 2011-190145 filed Aug. 31, 2011, the entire contents of which are incorporated herein by reference.
2. Description of the Related Art
Recently, television receivers have been developed to cope with various interfaces using different types of input terminals such as HDMI and analog input terminals (NTSC) in conjunction with tuners for receiving and reproducing television signals. Patent Document 1 discloses an example of a television receiver equipped with digital input terminals such as an HDMI (High-Definition Multimedia Interface) and a DVI (Digital Video Interface), each of which is selectively used. Additionally, some television receivers have been designed to incorporate memory card slots. Input terminals of television receivers can be connected to game devices, Internet-connectible personal computers, home video devices, or the like.
Since television broadcasting stations optimize television signals representing video images and audio sounds to secure high-quality reproduction in advance, the tuners of television receivers are able to demodulate television signals and reproduce video images and audio sounds with a high quality. In contrast, video images produced by nonprofessional users using personal computers or home video devices are not optimized to secure high-quality reproduction, and video images downloaded from the Internet are compressed at a high compressibility and are not necessarily suited to high-quality reproduction. Video images shot by nonprofessional users are rarely adjusted in terms of audio/video quality after shooting, so that the audio setting thereof may be fluctuated to produce higher/lower sound volumes than expected sound volumes. Such video images may be occasionally reproduced with extremely high or low sound volumes. Additionally, video images may be compressed by eliminating high-pitch registers in order to achieve a high compressibility. For this reason, it is necessary to improve audio processing of audio/video apparatuses so that audio sound can be reproduced in an articulate manner depending on its video reproduction quality.
In general, video files recorded on video recording media include various pieces of attribute information, such as device-type information of cameras used for video shooting, video compressing algorithms, resolutions, color-bit counts, frame rates, audio compressing algorithms, sampling rates, sample-bit counts, and bit rates. In contrast, video data input to video input terminals such as HDMI and analog input terminals are streaming signals which are decoded and reproduced by external devices, so that video data may have lost attribute information thereof. For this reason, it is difficult for television receivers to determine how to process video data with articulate sound reproduction.
Audiovisual (AV) amplifiers equipped with video input terminals such as HDMI and analog input terminals can be used to supply video data to television receivers and implement audio functionality for producing sounds via speakers. However, AV amplifiers have undergone the foregoing drawback as well.
As sound processing, it is possible to employ various techniques such as dynamic range compression and frequency component compensating extension/enhancement, demonstrating a richness of sound elements. Patent Document 2 discloses a sound volume controller achieving real-time dynamic range compression, whilst Patent Document 3 discloses a sound effect imparting device achieving high-pitch extension and low-pitch enhancement. These audio processing techniques have been developed independently of video processing and are not necessarily adapted to video processing of television receivers yet.